The present invention relates to pneumatic power hand tools, more particularly, the present invention relates to hand held, pneumatic screw tools.
In the case of known Hydro-Impulse Screw Tools the main lamellas are pressed against the elliptical interior walls of the hammer mechanism. The additional lamellas have been manufactured of one piece together with the output shaft and are staggered to the middle of the hammer mechanism. This way the main lamellas and the additional lamellas only contact the associated seal of the hammer mechanism's housing once in a 360.degree. rotation of the hammer mechanism's housing, so that an impulse to the output shaft is generated at that moment.
The seal strips and the additional lamellas must be precisely manufactured in order for the additional lamella which forms one piece with the output shaft to seal against the associated cover strips of the hammer mechanism's housing without encountering obstructions. This is the reason that this hydro-impulse screw tool can only be manufactured at large scale and great cost. Additionally, the bearings of the output shaft are subjected to a disproportionate load at the time of the turning impulse due to the asymmetrical distribution of the lamellas, so that the bearing positions are subjected to considerable loads leading to premature wearing out.